How to keep privilege like Dropbox to inject Finder

Question

I can inject Finder to put a button on toolbar and add a custom context menu. But my app ask me to input password to do this. How to keep privilege like dropbox, only need to input password one time no matter restart app or restart computer?

Answer 1

only need to input password one time

You'll want to look into the Keychain Services API.
They allow you to store user passwords and other authentication information in a secure and standard manner.

It's a plain C API but there are also wrappers for Cocoa out there.